There are fears that the media circus following the Duke and Duchess of Sussex could upstage the Platinum Jubilee. Photo / Getty Images
It was arguably one of the most awkward moments in modern royal memory - a strained engagement at Westminster Abbey that came to symbolise a family divided.
When the Duke and Duchess of Sussex carried out their final duty as senior royals by attending the Commonwealth Day Service in March 2020, the tension between the couple and the Cambridges could not have been more marked.
The Duke and Duchess of Cambridge were even forced to back out of the traditional royal procession at the last minute, after 2000 orders of service were printed without any mention of LA-bound Sussexes at all.
As the cameras panned in on the so-called "fab four" shifting uncomfortably in the pews, it appeared to signal the end of an era.
Little wonder, then, that nerves behind palace walls are once again being rattled as the House of Windsor prepares to welcome the erstwhile royals back into the fold.
Amid fears that another "Sussex bomb" is about to be dropped on the Queen's Platinum Jubilee celebrations, after their controversial Oprah Winfrey interview and news of the duke's forthcoming, warts-and-all autobiography, courtiers have been doing everything in their power to diffuse any potential flashpoints.
It has already been announced that the couple will not appear on the Buckingham Palace balcony if they attend Trooping the Colour on Thursday because, along with the Duke of York, they are no longer "working" royals.
Yet while the palace remains in control of the "official" engagements the couple plan to attend - they are on the guest list for Friday's Service of Thanksgiving at St Paul's Cathedral, although presumably not in the royal procession - the powers that be appear to have little knowledge of any of their "unofficial" plans.
Their habit of making unpublicised appearances, such as the duchess' recent visit to the memorial for murdered primary school children in Uvalde, Texas, has naturally led to concerns of a "circus" following their every move during the four-day extended bank holiday weekend.
The prospect of a Netflix film crew also making an appearance is said to be causing consternation, although the streaming giant has not applied for accreditation to film the public jubilee events.
The couple's team have previously denied a reality television show is in the works, but this month Page Six, the US celebrity gossip page, reported Netflix is now filming an "at home with the Duke and Duchess of Sussex-style docuseries".
With Archie, 3, and Lilibet, who turns 1 on Saturday, also in tow, there is no guarantee against the Sussexes "freelancing" - not only in terms of their charitable endeavours, but also in regards to their personal relationship with the 96-year-old monarch. Their whistlestop visit to see Her Majesty at Windsor Castle en route to last month's Invictus Games at The Hague appeared to take some of the Queen's nearest and dearest by surprise.
The couple retain patronages in a handful of UK charities, including Wellchild and Smartworks. The duchess is thought to have stayed in touch with the women of the Hubb Community Kitchen at Grenfell Tower. It is not known whether they plan to attend any events planned by these organisations while they are here.
So is the duke and duchess' presence likely to be explosive as feared - or more of a damp squib?
The Montecito-based couple's people have been busily playing down any suggestion that they will upstage the Queen as she marks 70 years on the throne.
As a source told The Telegraph last week, they will stick to the script by "avoiding visits elsewhere".
The palace also appears to be unaware of any potential competing engagements, with one insider revealing: "I don't think they're doing much. I wouldn't be surprised if they just do Trooping and the service and that's it."
Talk of the couple seeking to christen Lilibet while she is in Britain and meeting her great-grandmother and namesake for the first time appear wide of the mark. As one source put it: "It's already an incredibly busy weekend for the Queen, I don't think anyone would also want to wish a Christening on her." The Archbishop of Canterbury, the Most Rev Justin Welby, testing positive with Covid also appears to have put paid to that rumour.
Intriguingly, it appears the couple will not be accompanied to the UK by any of their own public relations representatives after Toya Holness, their former spokesman, left Archewell earlier this month.
Liaison between the Sussexes and the Palace is being handled by Herlihy Loughran, an "advisory partnership" comprised of Clara Loughran and Beth Herlihy, former palace aides. The duo handled the communications for the Invictus Games and are said to be the duke's "eyes and ears" back in Britain.
Meanwhile, The Telegraph understands that conversations have taken place to establish what the Cambridge children - Prince George, Princess Charlotte and Prince Louis - are attending, in a bid to match them up with their American cousins.
As such, none are expected at the thanksgiving service - with the jury still out on their presence at Trooping the Colour, the Party at the Palace on Saturday night or the Pageant in the Mall on Sunday afternoon.
Security remains a key concern for the Duke of Sussex, who is suing the Home Office over its decision to strip his family of their Metropolitan Police bodyguards. It is thought the Sussexes will be enveloped into the policing provision for all the royals while they are here.
For one weekend only, then, it is hoped the Sussexes will not just take one for the team - but be the team players The Firm once loved, and lost.